TROUBLESHOOTING /SYSTEM PERFORMANCE

A-3. Drop in moving speed

Checking moving speed

When a user complains that the machine cannot move at full speed , first measure the moving speeds in the work mode (fixed in the 1st gear) and then in the travel mod e (AUTO) for both the forward and reverse directions in order to determine whether the user feels the machine to be too slow although the speeds are normal or the vehicle is truely too slow due to s ome malfunction. Measure the driving speed in accordance with the description in the measurements of system p erformance.

Too slow speed in all modes

Insufficient engine power

Work mode : standard speed Travel mode : maximum speed is not reached

Dragging brakes (service, parking)

（１）Insufficient engine power (lack of speed)

Standard speeds

Normal

Measure the engine maximum speed with no load and the speed with the shovel lifted. Measure the maximum no-load engine speed in accordance with the description in the section of measurements of engine performance, 「Engine speed」．

Below standard value

Find out causes for too low speed even with no load on the engine.

1. Accelerator linkage is faulty, so the maximum speed position cannnot be reached even if the pedal is fully depressed.

2. The fuel filter and air filter are clogged.

3. The fuel pump and nozzles are faulty.

4. There are other faults in the engine.

Standard value

Measurement of speed with shovel raised

1.Lift arm to the highest position

2.Measure the engine speed during operation of the shovel main relief valve by keeping the lever in the "Raise" position.

3.Refer Performance standard list for standard value.

Below standard value

Standard value

Repair the engine

Dragging brakes (service, parking)

Troubleshooting

TROUBLESHOOTING /SYSTEM PERFORMANCE

A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

（１）Faulty mode selector switch or electrical wiring（YUKEN）

Check that, when the mode selector switch is changed from "work mode" to "travel mode", the "tortoise" lamp in the meter panel goes off and the " rabbit" lamp illuminates.

Abnormal

Check and replace the selector switch.

Normal

Measure the terminal voltage of the mode selector solenoid.

1. Disconnect the connector ① of the mode selector solenoid valve.

2. Measure the voltage between terminals of the machine side harness connector of the connector ①, when the starter switch is set to "ON" and the mode selector switch is set to the "travel mode."

3. Standard value: 0 V

In normal condition, voltage is present when the mode selector switch is set to the "work mode" and no voltage is present when it is set to the "travel mode".

Faulty wiring between mode selector switch and mode selector solenoid

Faulty operation of mode selector solenoid valve

Troubleshooting

TROUBLESHOOTING /SYSTEM PERFORMANCE

A-4. Movement speed is normal in "work mode" (LOW) but top speed is not reached in "travel mode" (AUTO).

mode selector switch or electrical wiring（ＵＣＨＩＤＡ）

Check that, when the mode selector switch is changed from "work mode" to "travel mode", the "tortoise" lamp in the meter panel goes off and the " rabbit" lamp illuminates.

Check and replace the selector switch.

Measure the terminal voltage of the mode selector solenoid.

1. Disconnect the connector ① of the mode selector solenoid valve.

2. Measure the voltage between terminals of the machine side harness connector of the connector ①, when the starter switch is set to "ON" and the mode selector switch is set to the "travel mode."

3. Standard value: 0 V In normal condition, voltage is present when the mode selector switch is set to the "work mode" and no voltage is present when it is set to the "travel mode"

Faulty wiring between mode selector switch and mode selector solenoid

Faulty operation of mode selector solenoid valve

Troubleshooting